Significant disparities exist in prostate cancer treatment and survival between African-American and Caucasian men. Although most prior research has focused on the contribution of individual biological, behavioral and socioeconomic characteristics to these disparities, these individual characteristics comprise only one part of the picture. There is a pressing need to understand how the social environment contributes to racial disparities in prostate cancer in the US. Residential segregation is increasingly recognized as having a powerful relationship with the health of African-Americans. Prior scholarship has identified several pathways by which segregation may affect health including its effects on socioeconomic deprivation, neighborhood resources, exposure to violence and access to medical care among African-Americans. In this project, we will extend current theories of the relationship between segregation and health by examining a novel behavioral pathway by which segregation may lead to poor health outcomes among African-Americans - the use of low quality health care providers and facilities. This theory builds on prior work demonstrating strong correlation between cancer outcomes and hospital and provider characteristics, prevalent distrust of research/teaching hospitals among African-Americans, and a link between residential segregation and racial alienation. The unifying hypothesis guiding this project is that residential segregation correlates with worse prostate cancer outcomes among African-American men, that the effect of segregation contributes to racial disparities in outcomes, and that this effect is mediated, in part, through differential use of low quality hospitals and providers. To test this hypothesis, we propose to conduct a multi-level analysis, linking individual-level data about prostate cancer treatment and outcomes from national Medicare files to hospital and provider-level data about case volume and teaching status and to community-level data about residential segregation. Guided by our conceptual model, we will use a staged analytic plan to investigate the association between race and prostate cancer outcomes, the relationship among segregation, race and prostate cancer outcomes, and the pathways by which segregation may affect these outcomes. We will assess the effects of segregation within each racial group, and the interaction between segregation and race within the overall cohort.